Known bearing units, in their more general configuration, comprise a rolling bearing provided with an outer ring, an inner ring defining together with the outer ring an interspace, a row of rolling elements arranged inside the interspace in order to allow the relative rotation of the outer ring and the inner ring, and a housing body inside which the rolling bearing is housed and which is provided with a radial flange for connection to the bearing unit of a respective agricultural disc.
Moreover, the rolling bearing is also provided, on both its axial sides, with two sealing devices, which are designed to prevent the entry, into the rolling bearing, of contaminants (mud, straw, sand, grit, etc.) and are usually composed of a metal support, joined together with one of the two rings so as to extend at least partly inside the interspace, and one or more sealing lips which are made of rubbery material and which, fixed to the metal support, make sliding contact or not with the other ring.
It is well known that agricultural applications represent one of the most aggressive environments for rolling bearing units in particular owing to the nature and the diversity of the possible contaminants. Therefore, in order to safeguard as far as possible the working life of the rolling bearings which, however, still remains one of the shortest in the sector, the sealing devices have been increasingly improved, made more sophisticated and their capacity increased by increasing the number of sealing lips or modifying their configuration or by increasing also the number of metal supports provided with lips fixing them to either one of the two rings of the rolling bearings. All these solutions hitherto, if, on the one hand, they have proved to be useful by increasing the working life of the rolling bearings, on the other hand, have resulted not only in an increase in the complexity of the bearing units for agricultural use, with a consequent increase in the production time, but also in an increase in the production costs.